Uranium Development & Exploration The Athabasca Basin Investor Update – April 2018 Cautionary Statements & References Cautionary Statements: This presentation includes forward-looking information or forward-looking statements under Canadian and U.S. securities laws that involve risks, uncertainties and other factors that could cause actual results to differ materially from those expressed or implied by such forward-looking statements. Factors that could cause differences may include: the speculative nature of exploration and development projects, the failure of Denison to realize benefits from transactions, Denison’s inability to expand and replace its mineral reserves and resources and the imprecision of mineral reserves and resources estimates, the impact of volatility in uranium prices on the valuation of mineral reserves and resources and the market price of Denison’s shares, unexpected development and operating risks, delays in obtaining permits and licenses for development properties, reliance on other operators and partners, and uncertainty surrounding Denison’s successful completion of exploration plans, timely completion economic analyses (including a PEA or PFS), the ability to reach revenue targets, and the ability to operate within budget. In addition, we have made assumptions in drawing the conclusions contained in these statements, including assumptions regarding future demand for uranium, production levels and costs, mining conditions, relationships with partners, and our ability to continue our operations without any significant disruptions. Additional information about the material factors that could cause the results to differ materially, and the material assumptions we have made, are contained in our current Annual Information Form and our current annual MD&A, which are available on SEDAR. Forward-looking information is designed to help you understand management’s current views of our near and longer-term prospects, and it may not be appropriate for other purposes. We will not necessarily update this information unless we are required to by securities laws. This presentation may use the terms “measured", “indicated“, “inferred" and “historical” mineral resources. U.S. investors are advised that, while such terms are recognized and required by Canadian regulations, the Securities and Exchange Commission does not recognize them. “Inferred mineral resources" and “historical estimates” have a great amount of uncertainty as to their existence and great uncertainty as to their economic feasibility. It cannot be assumed that all or any part of an inferred mineral resource or a historical estimate will ever be upgraded to a higher category. Under Canadian rules, estimates of inferred mineral resources may not form the basis of feasibility or other economic studies. Further, historical estimates are not recognized under Canada’s NI 43-101. U.S. investors are cautioned not to assume that all or any part of measured or indicated mineral resources will ever be converted to mineral reserves. Technical Report References: • McClean Lake “Technical Report on the Denison Mines Inc. Uranium Properties, Saskatchewan, Canada” dated February 16, 2006. Richard E. Routledge, M.Sc., P. Geo. and James W. Hendry, P. Eng., are the independent Qualified Persons for the McClean Technical Report for the purposes of the requirements of NI 43-101. • McClean Lake - Sue D “Technical Report on the Sue D Uranium Deposit Mineral Resource Estimate, Saskatchewan, Canada”, dated March 31, 2006. Richard E. Routledge, M.Sc., P. Geo. and James W. Hendry, P. Eng., are the independent Qualified Persons for the Sue D Report for the purposes of the requirements of NI 43-101. • McClean Lake – McClean North "Technical Report on the McClean North Uranium Deposit Mineral Resource Estimate, Saskatchewan, Canada", dated January 31, 2007. Richard E. Routledge, M.Sc., P. Geo. is the independent Qualified Person for the McClean North Technical Report for the purposes of the requirements of NI 43-101. • Midwest "Technical Report on the Midwest Uranium Deposit Mineral Resource and Mineral Reserve Estimates, Saskatchewan, Canada" (the "Midwest Technical Report") dated February 14, 2006. Richard E. Routledge, M.Sc., P. Geo., James W. Hendry, P. Eng. and Luke Evans, M.Sc., P. Eng. are the independent Qualified Persons for the Midwest Technical Report for the purposes of the requirements of NI 43-101. • Midwest – Midwest A “Technical Report on the Midwest A Uranium Deposit of Saskatchewan, Canada” (the “Midwest A Technical Report”) dated January 31, 2008. Michel Dagbert, P. Eng is the independent Qualified Person for the Midwest A Technical Report for the purposes of the requirements of NI 43-101. • Waterbury “Mineral Resource Estimate On The J Zone Uranium Deposit, Waterbury Lake Property” (the "J Zone Technical Report"), dated September 6, 2013. Allan Armitage, Ph.D., P.Geol., and Alan Sexton, M.Sc., P.Geol.,are the independent Qualified Persons for the J Zone Technical Report for the purposes of the requirements of NI 43-101. • Wheeler River: (1) “Technical Report on a Mineral Resource Estimate for the Wheeler River Property, Eastern Athabasca Basin, Northern Saskatchewan, Canada.” Nov. 25, 2015 with material change made to the resource on January 31,2018. William E. Roscoe Ph.D, P.Eng. and Mark B. Mathisen C.P.G. A copy of this report and the material change is available on SEDAR at www.sedar.com . William E. Roscoe, Ph.D, P. Eng., is the independent Qualified Person for the Report for the purposes of NI 43-101. and, (2) PRELIMINARY 1 ECONOMIC ANALYSIS FOR THE WHEELER RIVER URANIUM PROJECT, SASKATCHEWAN, CANADA” March 31, 2016. Ken Reipas, P. Eng. Uranium Market: Shifting Fundamentals? Utility Uranium Requirements (million pounds U3O8- per UxC Q1'18 • Sustained low spot and LT price 250 means very few new sources of supply in the pipeline 200 • ~1.8B lbs U3O8 in uncovered 150 Covered Demand demand by 2035 Covered Demand 100 • Uncovered utility demand Uncovered Demand reaches ~24% by 2021 and 50 ~62% by 2025 • Recent production cuts from 0 2021 2030 2019 2020 2022 2023 2024 2025 2026 2027 2028 2029 2031 2032 2033 2034 2035 world’s largest producers – 2018 including Cameco’s McArthur River / Key Lake operation in Uncovered US Utilities Uncovered Non-US Utilities *Covered does not include inventory the Athabasca Basin 2 Source: UxC Uranium Market Update Q1 2018, World Nuclear Association (“WNA”), Institute For Energy Research Infrastructure Rich Eastern Athabasca Basin McClean Lake Mill (Denison 22.5%) Waterbury Athabasca (Denison 64.2%) Hook-Carter Basin (Denison 80.0%) Rabbit Lake Mill Cigar Lake Mine Proposed ~45km road connection McArthur River Mine Wheeler River (Denison 63.3%) Key Lake Mine & Mill All season highway / haul road Provincial power grid 3 Potential to be Top 5 Producing Asset Top Producing Uranium Mines 2017 est. (1)(2) Million Pounds U3O8 vs. Wheeler PEA Production Plan M lbs. M lbs. Source: UxC Uranium Market Outlook Q4’17 20 18.0 18.0 15 M lbs. 9.6 M lbs. 10 M lbs. M lbs. 7.3 M lbs. M lbs. M lbs. M lbs. 6.6 6.3 5.8 5.5 5.5 5.0 5 - (1) IMPORTANT CAUTION REGARDING THE PRELIMINARY ECONOMIC ASSESSMENT (“PEA”): The PEA is preliminary in nature and includes inferred mineral resources that are considered too speculative geologically to have the economic considerations applied to them to be categorized as mineral reserves, and there is no certainty that the preliminary economic assessment will be realized. Mineral resources are not mineral reserves and do not have demonstrated economic value. See Press Release dated April 4, 2016 and Technical Report filed on SEDAR and EDGAR: “PRELIMINARY ECONOMIC ANALYSIS FOR THE WHEELER RIVER URANIUM PROJECT, SASKATCHEWAN, CANADA” March 31, 2016. Ken Reipas, P. Eng. (2) Based on Wheeler River average annual production (100% basis) per PEA 4 Project Development Scorecard Wheeler River is poised to be the next uranium development project in the Athabasca Basin region Project Development Criteria Wheeler River Ranking(1) Denison owns 22.5% of Ownership of licenced mill with excess capacity McClean Lake Mill 1st Provincial power line and Proximity to infrastructure highway on property 1st Estimated resources in M&I category 132M lbs U3O8 2nd Degree of confidence in estimated resources 97% of total resources in M&I 1st Overall Grade on existing M&I resources 3.3% U3O8 2nd Estimate of CAPEX required to build(2) (Lowest) CAD $560M 1st Timeline to Pre-Feasibility Study(3) (Shortest) ~6 months 1st Notes: (1) Rankings are based on comparison of undeveloped uranium projects (at 100% ownership) with total indicated resources greater than 40M lbs U3O8, located in the Athabasca Basin region – namely Arrow (NexGen Energy Ltd.), Triple R (Fission Uranium Corp.), Millennium (Cameco, JCU), Shea Creek (Areva, UEX Corp.), Midwest (including the Midwest and Midwest A deposits)(Areva, Denison, OURD). All numbers used in comparisons have been taken from corporate presentations, technical reports, website disclosure and/or news releases available on their respective websites or SEDAR. (2) CAPEX estimates are per NI 43-101 technical reports. Certain projects do not have NI 43-101 5 estimates of upfront capital costs. (3) Timeline to feasibility is based on company disclosures / guidance. M&I Resources Available for Pre-Feasibility Studies 180 Wheeler River is the largest undeveloped ) 8 O 160 3 uranium project in the infrastructure rich 140 eastern Athabasca Basin M LBS LBS U M 120 100 80 M&I RESOURCES ( RESOURCES M&I 60 40 20 0 Arrow (West) 2,3 Wheeler River Triple R (East) (West) Millennium (East) Shea Creek 4 (West) Midwest (East) (1) All M&I resource numbers are on 100% basis and have been sourced from company reports and/or corporate websites as reported February 2018. (2) See Denison news release dated January 31st, 2018 for additional technical information and notes on quality control. (3) See important cautionary information about the Wheeler River technical report and qualified persons pertaining to the resource estimate update on slide 4 and Denison’s news release dated January 31, 2018.